Planning the route
of a hike yourself is time-consuming and challenging, but can be
great fun. The more I do it, the better I get and the more I enjoy
it. Here is some advice for people planning similar hikes.
This post is geared towards planning hikes in Europe, but you might
find interesting tips here even if you are planning your own route in
other continents.

Planning a route for
long distance hike of 1,000 km and more I go through three phases:

Phase 1: Rough
planning

My long hikes
usually start with an idea like hiking across Germany or the UK or
finding a route across Europe incorporating the big mountain ranges.
I always try to use existing marked trails as much as possible
instead of creating free style cross country routes. This has several
reasons: First of all I like hiking without having to spend too much
time navigating. On marked trails I just have to follow the blazes. I
only occasionally have to look at a map or my GPS to check where I
am. This is far less time and energy consuming than going freestyle
where you constantly have to check map, compass and/or GPS. Another
advantage is that you can usually buy strip maps or hiking guides for
established long-distance trails which ends up to be much cheaper and
lighter than buying the relevant topo maps which contain a lot more
information than you need - especially if the sheet lines are
unfavorable. In the hiking guides or relevant websites for a
long-distance trail you will also find a lot of useful logistical and
tourist information that facilitates your logistical
planning.

In the rough
planning phase I therefore try to find a good overview map of the
region showing all the long-distance trails. I
personally prefer paper maps in this stage,
but unfortunately these are not readily available for all European
countries. Here are some good examples:

Based on these
overviews maps I get a very good idea of the feasibility of a route.
Are there enough existing trails that can be connected? Are there
many obstacles like long road walks or high mountain ranges in
winter? When I have a rough idea of the route I proceed to phase 2,
the detailed planning.

Phase 2: Detailed
planning

Goal of this phase
is to create a gpx track for the whole route. This track
will be the guideline for my entire hike and therefore I plan the
route down to the last meter. I am aware that I will most likely
deviate from this route occasionally out of various reasons like
short cutting, sightseeing, resupplying, seeing a nicer route etc.
But I want to have the gpx track as a fall back strategy in case I
don't have detailed map or I am just too plain lazy to find a better
route. I also need a continuous route as a gpx track in order to
calculate the length of my hike which is essential for estimating the
time needed for the hike and planning resupply.

Again it helps to
use existing long distance trails and connect them because they
usually have a website of their own and/or you can find free gps
track downloads for them on the internet. Good sources are for
example:

Unfortunately, I
cannot always link existing trails together. Sometimes I have to
bridge gaps by planning a freestyle route. With freestyle routes I
mean creating my own route using roads, forest roads and all sorts of
other trails that are not marked and/or part of long-distance trail.
I use Garmin topo maps or OSM maps as a planning base. This freestyle
route walking is much easier in Europe than in the US because in
Europe you are almost always allowed to walk on any trail or forest
road even if it is on private property.

Still planning
freestyle routes can be tricky: What looks like a perfect trail or
forest road on Garmin topo or OSM can in reality be non-existent,
overgrown, flooded, eroded or otherwise impassable. Never rely on a
single unmarked trail that is shown on a map. Have alternatives handy
in case that this trail does not exist or is impassable.

The accurateness of
the calculation of the trip length in kilometers and time will depend
on the quality of the downloaded gpx tracks. If these tracks have
plenty of track points like one track point every 15 to 20 meters,
the overall length of the track will be reliable. But very often
these gpx tracks have been cut down to reduce the amount of track
points. These becomes a big problem especially in mountainous
regions. Your gpx track might have only two track points with a
straight line of a couple of hundred meters between them. In reality
there might be a trail with several switchbacks and a couple of
kilometers between those two track points! This can add up quickly
and distort the real length of a trail tremendously. And all of a
sudden you'll need one day more to get to your next resupply
point.... Always check the quality of the gpx tracks you have
downloaded. The less trackpoints per kilometer is has the more
buffer you should add to the length of your route. If in doubt I
usually add 10-15% to the track length.

In this phase I also plan alternate routes. These come in very useful in two
cases:

I try to plan
shorter alternate route for the end of my hike in case I unexpectedly
run out of time but still want to make it to the finish point. I also
plan alternates for long stretches that can be difficult in bad
weather like exposed mountain ridges. The better your map material is
the less need you have to plan alternates because you can plan them
“on the spot” whenever the need for an alternate arises. But very
often I won't carry detailed maps for an area or only strip maps that
don't show enough of the surrounding area to plan an alternate.
Having a pre-planned alternate can be essential then.

On tour I don't want
to solely rely on my GPS for navigation. Already twice may GPS broke
on trail and I would have been lost without paper maps. I therefore
try to carry paper maps for my route or buy them along the way.
Again, using existing long-distance trails makes this easier because
very often strip maps and/or guidebooks are available for them. In
Spain look for guidebooks (topoguias) of
Prames
and in France for the “topoguides” of the
FFRP.
Of course I cannot carry maps for a several thousand kilometer hike.
I therefore try to buy the maps/guidebooks as I go, but it has proven
to be very useful to determine beforehand which map/guidebook I need.

If I cannot find
strip maps/guidebooks or if I hike a long freestyle stretch I print
out the relevant maps using the map material of my Garmin topos or
OSM maps. Sometimes there are better free or cheap alternatives like

I very rarely buy
normal paper maps when hiking long distance because these maps are
too expensive and too heavy for my purposes especially when the sheet
lines are unfavorable.

Phase 3: Logistical
planning

Goal of this phase
is to create a document containing all the logistical information
needed for my hike. I'll carry this document in paper and as a file
on my smartphone. Keep in mind that you'll need to have your route
fully planned in order to sensibly plan the logistics. This little
guidebook contains the following information:

Resupply: I can
carry food for up to 8 or 9 days, but in Europe you almost always
find resupply options more often, especially if you are willing to
deviate from the hiking trail. Still, I don't want to find the next
supermarket by coincidence with an empty stomach – I therefore
research ahead where there are resupply options along my route. In
bigger cities there will definitely be supermarkets, but it still
helps to avoid long detours on pavement if you know exactly where
they are. It is much more difficult to research resupply options in
little villages or towns. Here are some tipps:

Research with google
maps is quick and easy, but has a
lot of disadvantages. First of all not all supermarkets are listed
there. This especially applies to little mom-and-pop-stores. Also not
all supermarkets that show up on google maps do exist any longer.
Very often the data have been entered, but not updated. The only way
to make sure that the store is still there is to double check with
other data sources like a supermarket chain's own website or just
calling by phone. This is a lot of work but definitely worthwhile if
you are relying on one store with no other back up options nearby.

In Mediterranean
countries shops are closed midday for lunch break. These lunch breaks
are several hours long and can be anything from noon to 5 pm. If you
don't want to wait in front of a closed shop with an empty stomach it
helps to research opening times beforehand or at least note the phone
number so that you can call ahead and find out.

In google maps you
can save the location of a store under “my places”. You'll have
to convert the waypoint then and can transfer it onto your GPS. Some
supermarket chains like “Lidl” offer a download of all their
locations as waypoints
facilitating resupply research tremendously.

Consumables: These
are mostly shoes, fuel and maps/guidebooks. For shoes, gas canisters
and maps I try to locate outfitters along the route and note down
their location, opening times and phone numbers. I use gas canisters
and their resupply is essential for me. I therefore always call ahead
to find out if they carry canisters and the shoes I need. For
Campingaz canisters the Campingaz website offers a great
international store locator. For maps and guidebooks you don't need
an outfitter – any book shop will usually do. Again it is important
to note down their phone numbers. Call ahead several days in advance
to find out if your map or guidebook is available and let them
reserve it. If they don't stock it, it can usually be ordered within
a couple of days and then picked up in the store.

General delivery or
poste restante: Although I try to avoid sending stuff via Poste
Restante there are some cases when this becomes necessary. In some
countries I cannot buy the trail runners I need and have to have them
shipped to a post office along the route. If I
already own the maps/guidebooks I need for an upcoming stretch but
don't want to carry them hundreds of kilometers before I use them I ship them via Poste Restante.
Keep in mind that regulations for Poste Restante vary tremendously
from country to country. Always make sure what they are. Some
countries only accept small packages up to 2 kg as Poste restante.
Sometimes your delivery will be kept 2 weeks, sometimes 1 month.
Delivery times can be unreliable and there always is the risk of
loss. Always try to send a resupply package to a town where you are
planning on having a rest day anyways. Then you don't have to worry
about arriving on a Sunday.

Tourist information:
If there are attractions along my route that I definitely want to
visit I research opening times beforehand. I don't want to arrive on
the only day when the sight is closed. If I know where I
want to have rest day I try to research cheap accommodation like
hostels and note down their phone number. This way I can call ahead
and make reservations.

It depends on your
personal preference to what extent you research logistical
information. You can of course do most of this research on the go,
especially if you are carrying a smart phone. Still I personally
prefer doing most of this research at home where it is much easier
with a fast internet connection, a keyboard and a mouse
than with a tiny smartphone display and a touchpad. On tour I very
often encounter no or very weak cell phone reception resulting in no
or very slow internet. Also surfing the internet drains the batteries
very fast.